The ephemeral accountable care organization-an unintended consequence of the Medicare shared savings program.

A fundamental element of health care payment reform under the Affordable Care Act is the development of Accountable Care Organizations (ACOs). The ACO model employs shared-risk contracts to better align the interests of health care providers and payers with the intent of driving efficiency and quality in care. The Medicare Shared Savings Program is the most popular of the Medicare ACO programs, with over 200 health systems across the nation participating at this time. However, a pitfall in the way that the Medicare Shared Savings Program is structured, specifically the benchmarking and rebasing method, could make it difficult for even top-performing ACOs to achieve sustained success, thereby threatening the long-term viability of the program. In this paper, we present this pitfall to the radiology community as well as potential solutions that can be considered by CMS moving forward.